Fixes bug introduced by myself in BulletModel::ComputeMaximumDepthCollisionPoints.
Fixes bug introduced by myself in BulletModel::ComputeMaximumDepthCollisionPoints.

billhoffman/drake,sheim/drake,billhoffman/drake,sheim/drake,billhoffman/drake,sheim/drake,sheim/drake,sheim/drake,billhoffman/drake,billhoffman/drake,billhoffman/drake,sheim/drake,sheim/drake,billhoffman/drake,billhoffman/drake,sheim/drake